Method and apparatus of color system adaptive intensity compensation and video encoding/decoding method and apparatus thereof

ABSTRACT

A method and apparatus for encoding and/or decoding image data. The encoding method includes: if the color space of an image is a single color space, correcting pixel values by applying identical correction pixel values to all color components of a previous image, and if the color space of the image is not a single color space, correcting pixel values by applying different correction pixel values to the color components of the previous image; performing temporal prediction encoding of a current image by using the corrected pixel values of the previous image; quantizing the prediction encoded data; and generating a bitstream by entropy encoding the quantized data. According to the method and apparatus, when the pixel values of a previous image are desired to be corrected in order to perform temporal prediction encoding, different pixel value correction methods are applied according to whether or not the characteristics of color components included in the color space of the image desired to be encoded. By doing so, when image data is encoded, the encoding can be performed adaptively to a variety of color spaces and higher compression efficiency can be maintained.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2005-0064288, filed on Jul. 15, 2005, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for encodingand/or decoding image data, and more particularly, to an image encodingand/or decoding method and apparatus for performing temporal predictionencoding by correcting the pixel values of a previous image in order toincrease encoding efficiency.

2. Description of Related Art

When an image is taken by a camera, the image generally has an RGB (red,green, blue) color space. This RGB image is used after converting thecolor space to fit each application field. As a color space that hasbeen generally widely used in the video compression field, there is aYCbCr color space. Here, Y indicates a luma component and Cb and Crindicate chroma components. However, since there is a limit toexpression of a high picture quality in the YCbCr, an RGB color space oran XYZ color space is used in order to express a high picture quality.

Meanwhile, when moving pictures are compressed, temporal predictionencoding is performed, in which a current image is subtracted from aprevious image and the result is encoded. At this time, the compressionefficiency can be increased by performing prediction encoding moreaccurately with values obtained by modifying pixel values of theprevious image by using a predetermined weight value. Here, the methodof modifying the pixel values of the previous image is referred to aspixel value correction.

In the conventional image compression, when a series of imagescontinuous with respect to time are encoded, the images are compressedthrough temporal prediction in order to remove redundant informationbetween the previous image and the current image. In the Society ofMotion Picture and Television Engineers (SMPTE) Standard for Television:VC-1 Compressed Video Bitstream Format and Decoding Process (VC-1) thathas been undergoing standardization recently, a variety of temporalprediction methods are provided. Among the methods, there is a pixelvalue correction method in which the value of a previous image ismultiplied by or added to a predetermined value and then by using theresultant value, a current image is encoded. By using this method, theefficiency of the temporal prediction method can be increased to enhancethe compression ratio.

However, in the pixel value correction method used in the VC-1, theYCbCr color space is used as a fixed one. Though the YCbCr has beengenerally widely used for video encoding, the YCbCr has a limit topicture quality that can be expressed. When gradually increasing demandsfor high picture quality images are considered, a pixel value correctionmethod adaptive to a color space is required so that an identical methodcan be used to an image using a color space other than the YCbCr colorspace.

BRIEF SUMMARY

An aspect of the present invention provides a pixel value correctionmethod and apparatus adaptive to the color space of an image in an imagedata encoding and/or decoding method.

An aspect of the present invention also provides an image encodingand/or decoding method and apparatus using the pixel value correctionmethod and apparatus.

According to an aspect of the present invention, there is provided animage pixel value correction method of correcting the pixel value of aprevious image in order to perform temporal prediction encoding of acurrent image, the method including: correcting the pixel value of afirst color component among pixel values of the previous image, by usinga first proportional constant and a first offset value; determiningwhether or not the color space of the image is a single color space; andif the color space of the image is a single color space, correcting apixel value corresponding to a color component other than the firstcolor component, by using the first proportional constant and the firstoffset value, and if the color space of the image is not a single colorspace, correcting a pixel value corresponding to a color component otherthan the first color component, by using a second proportional constantand a second offset value, wherein the single color space is a colorspace in which each of color components includes both a chroma componentand a luma component. The second proportional constant may be differentfrom the first proportional constant, and the second offset value may bedifferent from the first offset value.

If the color space of the image is any one of YCbCr and YUV colorspaces, the first color component may be the Y component, and if thecolor space of the image is an RGB color space, the first colorcomponent may be the G component.

In the determining of whether or not the color space of the image is asingle color space, information on whether or not the color space of theimage is a single color space may be input by a user, or the color spaceof the image may be input by a user and it may be determined whether ornot the color space of the image is a single color space is input by auser.

In the determining of whether or not the color space of the image is asingle color space, if the color space of the image is an RGB colorspace, it may be determined that the color space of the image is asingle color space, and if the color space of the image is any one ofYCbCr and YUV color spaces, it may be determined that the color space ofthe image is not a single color space.

The correcting of the pixel value of the first color component mayinclude: generating correction pixel values by using the firstproportional constant and the first offset value; and by using thecorrection pixel values generated by using the first proportionalconstant and the first offset value, correcting the pixel value of thefirst color component.

In the correcting of the pixel value of the color component other thanthe first color component, if the color space of the image is a singlecolor space, the pixel value of the color component other than the firstcolor component may be corrected by using the correction pixel valuesgenerated by using the first proportional constant and the first offsetvalue.

The correcting of the pixel value of the color component other than thefirst color component, if the color space of the image is not a singlecolor space, may include: generating correction pixel values by usingthe second proportional constant and the second offset value; andcorrecting the pixel value of the color component other than the firstcolor component, by using the correction pixel values generated by usingthe second proportional constant and the second offset value.

According to another aspect of the present invention, there is providedan image pixel value correction apparatus of correcting the pixel valueof a previous image in order to perform temporal prediction encoding ofa current image, the apparatus including: a first correction valuegeneration unit generating correction pixel values by using a firstproportional constant and a first offset value; a color spacedetermination unit determining whether or not the color space of theimage is a single color space; a second correction value generationunit, if the color space of the image is not a single color space,generating correction pixel values by using a second proportionalconstant and a second offset value; and a pixel value replacement unit,if the color space of the image is a single color space, replacing thepixel values of all the color components of the previous image, with thecorrection pixel values generated in the first correction valuegeneration unit, and if the color space of the image is not a singlecolor space, replacing the pixel values of the first color componentwith the correction pixel values generated in the first correction valuegeneration unit and replacing the pixel values of the color componentsother than the first color component with the correction pixel valuesgenerated in the second correction value generation unit.

According to still another aspect of the present invention, there isprovided an image encoding method of encoding an image by using temporalprediction encoding, the method including: if the color space of animage is a single color space, correcting pixel values by applyingidentical correction pixel values to all color components of a previousimage, and if the color space of the image is not a single color space,correcting pixel values by applying different correction pixel values tothe color components of the previous image; performing temporalprediction encoding of a current image by using the corrected pixelvalues of the previous image; quantizing the prediction encoded data;and generating a bitstream by entropy encoding the quantized data.

According to yet still another aspect of the present invention, there isprovided an image encoding apparatus for encoding an image by usingtemporal prediction encoding, the apparatus including: a pixel valuecorrection unit, if the color space of an image is a single color space,correcting pixel values by applying identical correction pixel values toall color components of a previous image, and if the color space of theimage is not a single color space, correcting pixel values by applyingdifferent correction pixel values to the color components of theprevious image; a temporal prediction unit performing temporalprediction encoding of a current image by using the corrected pixelvalues of the previous image; a quantization unit quantizing theprediction encoded data; and an entropy encoding unit generating abitstream by entropy encoding the quantized data.

According to a further aspect of the present invention, there isprovided an image decoding method of decoding an image from an inputbitstream, the method including: entropy decoding the bitstream; inversequantizing the entropy decoded data; if the color space of an image is asingle color space, correcting pixel values by applying identicalcorrection pixel values to all color components of a previous image, andif the color space of the image is not a single color space, correctingpixel values by applying different correction pixel values to the colorcomponents of the previous image; and by using the corrected pixelvalues of the previous image, performing temporal prediction decoding ofdata corresponding to a current image among the inverse quantized data.

According to an additional aspect of the present invention, there isprovided an image decoding apparatus of decoding an image from an inputbitstream, the method including: an entropy decoding unit entropydecoding the bitstream; an inverse quantization unit inverse quantizingthe entropy decoded data; a pixel value correction unit, if the colorspace of an image is a single color space, correcting pixel values byapplying identical correction pixel values to all color components of aprevious image, and if the color space of the image is not a singlecolor space, correcting pixel values by applying different correctionpixel values to the color components of the previous image; and atemporal prediction decoding unit, performing temporal predictiondecoding of data corresponding to a current image among the inversequantized data, by using the corrected pixel values of the previousimage.

According to an additional aspect of the present invention, there areprovided computer readable recording media having embodied thereoncomputer programs for executing the pixel value correction methods orthe image data encoding and/or decoding methods.

Additional and/or other aspects and advantages of the present inventionwill be set forth in part in the description which follows and, in part,will be obvious from the description, or may be learned by practice ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages of the present inventionwill become apparent and more readily appreciated from the followingdetailed description, taken in conjunction with the accompanyingdrawings of which:

FIG. 1 is a block diagram showing a structure of an image encodingapparatus according to an embodiment of the present invention;

FIG. 2 is a block diagram of a pixel value correction unit of FIG. 1according to an embodiment of the present invention;

FIG. 3 is a flowchart of an image encoding method according to anembodiment of the present invention;

FIG. 4 is a flowchart of a pixel value correction operation of FIG. 3according to an embodiment of the present invention;

FIG. 5 is a block diagram of a structure of an image decoding apparatusaccording to an embodiment of the present invention; and

FIG. 6 is a flowchart of an image decoding method according to anembodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 1 is a block diagram showing a structure of an image encodingapparatus according to an embodiment of the present invention.

The image encoding apparatus of FIG. 1 includes a temporal predictionunit 100, a quantization unit 110, an entropy encoding unit 120, aninverse quantization unit 130, a temporal prediction decoding unit 140,a pixel value correction unit 150, and a memory 160.

The temporal prediction unit 100 extracts a block similar to a blockthat is currently desired to be encoded, among previous images stored inthe memory 160, and encodes the difference of the pixel value of theextracted previous image and the pixel value of the current image block.The quantization unit 110 quantizes the temporally predicted data andthe entropy encoding unit 120 generates a bitstream by performinglossless encoding of the quantized data and encoding information.

The data output from the temporal prediction unit 100 may pass through afrequency domain transform operation, such as a discrete cosinetransform (DCT), before the quantization. The inverse quantization unit30 inverse quantizes the quantized data output from the quantizationunit 110, and the temporal prediction decoding unit 140 restores animage by adding the prediction value used in the temporal predictionoperation, to the inverse quantized data. If the frequency domaintransform, such as the DCT, is performed before the quantization in theencoding, inverse frequency domain transform of the inverse quantizeddata may be performed. The pixel value correction unit 150 corrects thepixel values of the restored image and stores the correct image pixelvalues in the memory 160 in order to use the values in the temporalprediction of a next image.

FIG. 3 is a flowchart of an image encoding method according to anembodiment of the present invention, which will now be explained withreference to FIG. 1. The pixel value correction unit 150 corrects thepixel value of the previous image output from the temporal predictiondecoding unit 140 and stores the values in the memory 160 in operation300. The temporal prediction unit 100 extracts a block similar to thecurrent image block desired to be encoded, among previous images storedin the memory 160, and by using the difference of the pixel value of theextracted previous image block and the pixel value of the current imageblock, performs temporal prediction encoding of the current image blockin operation 310.

The quantization unit 110 quantizes the temporally predicted data inoperation 320, and the entropy encoding unit 120 generates a bitstreamby performing lossless encoding of the quantized data and encodinginformation in operation 330.

FIG. 2 is a block diagram of a pixel value correction unit of FIG. 1according to an embodiment of the present invention. The pixel valuecorrection unit 150 of FIG. 2 includes a color space determination unit200, a first correction pixel value generation unit 210, a secondcorrection pixel value generation unit 220, and a pixel valuereplacement unit 230. The operation of the pixel value correction unit150 of FIG. 2 will now be explained with reference to the flowchartshown in FIG. 4.

With respect to a first color component that is a reference among colorcomponents included in the color space of the image, the firstcorrection pixel value generation unit 210 generates correction pixelvalues by calculating according to the following equation 1 in operation400. If the color space is an RGB, the first color component that is thereference may be the G color component, and if the color space is aYCbCr or YUV, the first color component may be the Y color component.Y=SX+C  (1)Here, S is a proportional constant, C is an offset value, X is a pixelvalue desired to be corrected, and Y is a corrected pixel value. Theproportional constant S and offset value C may be preset by a user.Also, information on the applied proportional constant S and offsetvalue C may be included in the bitstream generated by the entropyencoding unit 120.

The color space determination unit 200 determines whether the colorspace of an image desired to be encoded is a single color space or acomplex color space in operation 410. In the single color space, colorcomponents included in the color space have similar characteristics.That is, each of the color components has a luma component and a chromacomponent. Since in the RGB color space each of the R, G, and B colorcomponents has a luma component and a chroma component, it may bedetermined that the RGB color space is a single color space.

In the complex color space, color components included in the color spacehave characteristics different to each other. Since in the YCbCr colorspace, the Y color component has a luma component, and the Cb and Crcolor components have chroma information, it may be determined that theYCbCr color space is a complex color space. Also, since the YUV colorspace the characteristics of the Y, U, and V color components aredifferent to each other, it may be determined that the YUV color spaceis a complex color space.

The color space determination unit 200 may determine the characteristicof the color space of the image, by receiving in input from the user ofinformation on whether the color space of the image desired to beencoded is a single color space or a complex color space. Also, thecolor space determination unit 200 may match each of a variety of colorspaces with information on whether the color space is a single colorspace or a complex color space, in advance and store the color spacesand corresponding information. Then, by receiving the name of the colorspace of an image desired to be encoded from the user, and using thestored information corresponding to the name, the color spacedetermination unit 200 may determine whether the color space of theimage is a single color space or a complex color space. The informationon whether the image is a single color space or a complex color spacemay be included in the bitstream generated in the entropy encoding unit120.

If the image desired to be encoded is a single color space, the pixelvalue replacement unit 230 replaces pixel values of each of all colorcomponents of the previous image with the correction pixel valuesgenerated in relation to the first color component in operation 420. Forexample, in the case of the RGB color space, by applying the correctionpixel values generated in relation to the G color component by the firstcorrection pixel value generation unit 210, to all the pixel values ofthe R, G, and B color components of the previous image, the pixel valuesare replaced by the correction pixel values.

If the image desired to be encoded is a complex color space, the secondcorrection pixel value generation unit 220 generates second correctionpixel values in relation to the color components other than the firstcolor component, by calculating the equation 1 in operation 430. Theproportional constant S and offset value C used to generate the secondcorrection pixel values may be different from the proportional constantS and offset value C, respectively, used to generate the firstcorrection pixel values.

The pixel value replacement unit 230 replaces the pixel values inrelation to the first color component of the previous image with thegenerated first correction pixel values in operation 440, and replacesthe pixel values in relation to the color components other than thefirst color component of the previous image with the generated secondcorrection pixel values in operation 450. For example, in the case ofthe YCbCr color space, the pixel values of the Y color component of theprevious image may be replaced with the first correction pixel values,and the Cr and Cb pixel values of the previous image may be replacedwith the second correction pixel values.

The pixel value replacement unit 230 stores the replacement pixel valuesof the previous image in the memory 160 in operation 460.

An example of a pseudo code showing a method of generating the firstcorrection pixel values and the second correction pixel values follows:if (LUMSCALE == 0) {   iScale = − 64   iShift = MAX * 64 − LUMSHIFT *2 *64   if (LUMSHIFT > 31)     iShift += HALF * 64; } else {   iScale =LUMSCALE + 32   if (LUMSHIFT > 31)     iShift = LUMSHIFT * 64 − 64 * 64;  else     iShift = LUMSHIFT * 64; } // Build Look Up Tables for (i = 0;i < MAX; i++) {   j = (iScale * i + iShift + 32) >> 6   if (j > MAX)    j = MAX   else if (j < 0)     j = 0   LUTY[i] = j   if( Single ColorSpace )     LUTUV[i] = j   else{     j = (iScale * (i − HALF) + HALF *64 + 32) >>6     if (j > MAX)       j = MAX     else if (j < 0)       j= 0     LUTUV[i] = j   } }

The values for LUMSCALE and LUMSHIFT are set by the user, andinformation on the specified values is included in the bitstreamgenerated by the entropy encoding unit 120.

Next, by using the set LUMSCALE and LUMSHIFT values, iScale and iShiftvalues are generated. By using the generated iScale and iShift values, alookup table, including correction pixel values corresponding to thepixel values of the previous image, respectively, is generated. By doingso, a lookup table (LUTY) in relation to the first color component and alookup table (LUTUV) in relation to the remaining color components aregenerated. The method of generating the lookup tables will now beexplained in more detail.

By using the generated iScale and iShift values, the lookup table (LUTY)including the correction pixel values in relation to the first colorcomponent is generated. Then, it is determined whether or not the imageis a single color space. If it is the single color space, the lookuptable (LUTUV) in relation to the color components other than the firstcolor component is generated in the same manner as the generated lookuptable in relation to the first color component.

If the image is a complex color space, by using the iScale and iShiftvalues, correction pixel values are newly calculated, and by using thenewly calculated correction pixel values, the lookup table (LUTUV) inrelation to the color components other than the first color component isgenerated.

In the pseudo code, MAX is the maximum value that a pixel value of theimage can have, and HALF is a half of the MAX. For example, when 8-bitimage data is used, MAX is 256 and HALF is 128.

FIG. 5 is a block diagram of a structure of an image decoding apparatusaccording to an embodiment of the present invention. The decodingapparatus of FIG. 5 includes an entropy decoding unit 500, an inversequantization unit 510, a temporal prediction decoding unit 520, a pixelvalue correction unit 530, and a memory 540. The operation of thedecoding apparatus shown in FIG. 5 will now be explained with referenceto a flowchart of an image decoding method according to an embodiment ofthe present invention shown in FIG. 6.

The entropy decoding unit 500 decodes an input bitstream and extractsencoded image data and encoding information in operation 600. Theinverse quantization unit 510 inverse quantizes the extracted image datain operation 610. The temporal prediction decoding unit 520 restoresimage data, by adding the corrected pixel values of the previous imagestored in the memory 540 to the inverse quantized data in operation 620.

For temporal prediction decoding of a next image, in operation 630, thepixel value correction unit 530 corrects the pixel values of the imagethat are temporal-prediction decoded and stores the result in the memory540 in operation 640.

The pixel value correction unit 530 corrects the pixel value of therestored image in the same method as the pixel value correctionperformed in the image encoding.

The entropy decoding unit 500 extracts information on the proportionalconstant S and offset value C, and information on whether the colorspace of the image is a single color space or a complex color space,from the input bitstream. By using the information on the proportionalconstant S and offset value C, and information on whether the colorspace of the image is a single color space or a complex color space,input form the entropy decoding unit 500, the pixel value of therestored image may be corrected.

The present invention can also be embodied as computer readable codes ona computer readable recording medium. The computer readable recordingmedium is any data storage device that can store data which can bethereafter read by a computer system. Examples of the computer readablerecording medium include read-only memory (ROM), random-access memory(RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storagedevices, and carrier waves (such as data transmission through theInternet).

In the image encoding and/or decoding apparatus according to theabove-described embodiments, when the pixel values of a previous imageare desired to be corrected in order to perform temporal predictionencoding, different pixel value correction methods are applied accordingto whether or not the characteristics of color components included inthe color space of the image desired to be encoded. By doing so, whenimage data is encoded, the encoding can be performed adaptively to avariety of color spaces and higher compression efficiency can bemaintained.

Although a few embodiments of the present invention have been shown anddescribed, the present invention is not limited to the describedembodiments. Instead, it would be appreciated by those skilled in theart that changes may be made to these embodiments without departing fromthe principles and spirit of the invention, the scope of which isdefined by the claims and their equivalents.

1. An image pixel value correction method of correcting a pixel value ofa previous image in order to perform temporal prediction encoding of acurrent image, the method comprising: correcting a pixel value of afirst color component among pixel values of the previous image using afirst proportional constant and a first offset value; determiningwhether a color space of the image is a single color space; andcorrecting a pixel value corresponding to a color component other thanthe first color component using the first proportional constant and thefirst offset value, when the color space of the image is a single colorspace, and correcting a pixel value corresponding to a color componentother than the first color component using a second proportionalconstant and a second offset value, when the color space of the image isnot a single color space, wherein the single color space is a colorspace having color components including a chrominance component and aluminance component.
 2. The method of claim 1, wherein the secondproportional constant is different from the first proportional constant.3. The method of claim 1, wherein the second offset value is differentfrom the first offset value.
 4. The method of claim 1, wherein, when thecolor space of the image is a YCbCr or a YUV color space, the firstcolor component is the Y component.
 5. The method of claim 1, wherein,when the color space of the image is an RGB color space, the first colorcomponent is the G component.
 6. The method of claim 1, wherein, in thedetermining of whether the color space of the image is a single colorspace, information on whether the color space of the image is a singlecolor space is input by a user.
 7. The method of claim 1, wherein, inthe determining of whether the color space of the image is a singlecolor space, the color space of the image is input by a user and it isdetermined whether the color space of the image is a single color spaceis input by a user.
 8. The method of claim 1, wherein, in thedetermining of whether the color space of the image is a single colorspace, when the color space of the image is an RGB color space, it isdetermined that the color space of the image is a single color space. 9.The method of claim 1, wherein, in the determining of whether the colorspace of the image is a single color space, when the color space of theimage is a YCbCr or a YUV color space, it is determined that the colorspace of the image is not a single color space.
 10. The method of claim1, wherein the correcting a pixel value of a first color componentcomprises: generating correction pixel values using the firstproportional constant and the first offset value; and correcting thepixel value of the first color component using the correction pixelvalues generated by using the first proportional constant and the firstoffset value.
 11. The method of claim 10, wherein, in the correcting apixel value of the color component other than the first color component,when the color space of the image is a single color space, the pixelvalue of the color component other than the first color component iscorrected using the correction pixel values generated using the firstproportional constant and the first offset value.
 12. The method ofclaim 10, wherein the correcting a pixel value of the color componentother than the first color component, when the color space of the imageis not a single color space, comprises: generating correction pixelvalues using the second proportional constant and the second offsetvalue; and correcting the pixel value of the color component other thanthe first color component using the correction pixel values generatedusing the second proportional constant and the second offset value. 13.An image pixel value correction apparatus for correcting the pixel valueof a previous image in order to perform temporal prediction encoding ofa current image, the apparatus comprising: a first correction valuegeneration unit generating correction pixel values using a firstproportional constant and a first offset value; a color spacedetermination unit determining whether the color space of the image is asingle color space; a second correction value generation unit generatingcorrection pixel values using a second proportional constant and asecond offset value, when the color space of the image is not a singlecolor space; and a pixel value replacement unit replacing the pixelvalues of all the color components of the previous image with thecorrection pixel values generated in the first correction valuegeneration unit, when the color space of the image is a single colorspace, and replacing the pixel values of the first color component withthe correction pixel values generated in the first correction valuegeneration unit and replacing the pixel values of the color componentsother than the first color component with the correction pixel valuesgenerated in the second correction value generation unit, when the colorspace of the image is not a single color space, wherein the single colorspace is a color space having color components including a chromacomponent and a luma component.
 14. The apparatus of claim 13, whereinthe second proportional constant is different from the firstproportional constant.
 15. The apparatus of claim 13, wherein the secondoffset value is different from the first offset value.
 16. The apparatusof claim 13, wherein, when the color space of the image is a YCbCr or aYUV color space, the first color component is the Y component.
 17. Theapparatus of claim 13, wherein, when the color space of the image is anRGB color space, the first color component is the G component.
 18. Theapparatus of claim 13, wherein the color space determination unitreceives an input of information on whether the color space of the imageis a single color space, and determines whether the color space of theimage is a single color space using the input information.
 19. Theapparatus of claim 13, wherein the color space determination unitreceives an input of the color space of the image, and determineswhether the color space of the image is a single color space.
 20. Theapparatus of claim 13, wherein, when the color space of the image is anRGB color space, the color space determination unit determines that thecolor space of the image is a single color space.
 21. The apparatus ofclaim 13, wherein, when the color space of the image is a YCbCr or a YUVcolor space, the color space determination unit determines that thecolor space of the image is not a single color space.
 22. An imageencoding method of encoding an image by using temporal predictionencoding, the method comprising: correcting pixel values by applyingidentical correction pixel values to all color components of a previousimage, when a color space of an image is a single color space, andcorrecting pixel values by applying different correction pixel values tothe color components of the previous image, when the color space of theimage is not a single color space; performing temporal predictionencoding of a current image using the corrected pixel values of theprevious image to yield prediction encoded data; quantizing theprediction encoded data to yield quantized data; and generating abitstream by entropy encoding the quantized data, wherein the singlecolor space is a color space having color components including a chromacomponent and a luma component.
 23. The method of claim 22, wherein thecorrecting pixel values of the previous image comprises: correcting thepixel value of a first color component among pixel values of theprevious image using a first proportional constant and a first offsetvalue; determining whether the color space of the image is a singlecolor space; and correcting a pixel value corresponding to a colorcomponent other than the first color component using the firstproportional constant and the first offset value, when the color spaceof the image is a single color space, and correcting a pixel valuecorresponding to a color component other than the first color componentusing a second proportional constant and a second offset value, when thecolor space of the image is not a single color space.
 24. The method ofclaim 22, wherein, when the color space of the image is a YCbCr or a YUVcolor space, the first color component is the Y component.
 25. Themethod of claim 22, wherein, when the color space of the image is an RGBcolor space, the first color component is the G component.
 26. Themethod of claim 23, wherein, in the determining whether the color spaceof the image is a single color space, when the color space of the imageis an RGB color space, it is determined that the color space of theimage is a single color space.
 27. The method of claim 23, wherein, inthe determining whether the color space of the image is a single colorspace, when the color space of the image is a YCbCr or a YUV colorspace, it is determined that the color space of the image is not asingle color space.
 28. The method of claim 23, wherein the correcting apixel value of the first color component comprises: generatingcorrection pixel values using the first proportional constant and thefirst offset value; and correcting the pixel value of the first colorcomponent using the correction pixel values generated using the firstproportional constant and the first offset value.
 29. The method ofclaim 23, wherein, in the correcting a pixel value of the colorcomponent other than the first color component, when the color space ofthe image is a single color space, the pixel value of the colorcomponent other than the first color component is corrected using thecorrection pixel values generated using the first proportional constantand the first offset value.
 30. The method of claim 23, wherein thecorrecting a pixel value of the color component other than the firstcolor component, when the color space of the image is not a single colorspace, comprises: generating correction pixel values using the secondproportional constant and the second offset value; and correcting thepixel value of the color component other than the first color componentusing the correction pixel values generated using the secondproportional constant and the second offset value.
 31. The method ofclaim 22, wherein, in the generating a bitstream, encoding is performedso that information on whether the image is a single color space isincluded in the bitstream.
 32. The method of claim 22, wherein, in thegenerating a bitstream, encoding is performed so that the firstproportional constant and the first offset value are included in thebitstream.
 33. The method of claim 22, wherein, in the generating abitstream, when the image is not a single color space, encoding isperformed so that the second proportional constant and the second offsetvalue are included in the bitstream.
 34. An image encoding apparatus forencoding an image using temporal prediction encoding, the apparatuscomprising: a pixel value correction unit correcting pixel values byapplying identical correction pixel values to all color components of aprevious image, when the color space of an image is a single colorspace, and correcting pixel values by applying different correctionpixel values to the color components of the previous image, when thecolor space of the image is not a single color space; a temporalprediction unit performing temporal prediction encoding of a currentimage using the corrected pixel values of the previous image to yieldprediction encoded data; a quantization unit quantizing the predictionencoded data to yield quantized data; and an entropy encoding unitgenerating a bitstream by entropy encoding the quantized data, whereinthe single color space is a color space having color componentsincluding a chroma component and a luma component.
 35. The apparatus ofclaim 34, wherein the pixel value correction unit comprises: a firstcorrection value generation unit generating correction pixel valuesusing a first proportional constant and a first offset value; a colorspace determination unit determining whether the color space of theimage is a single color space; a second correction value generation unitgenerating correction pixel values by using a second proportionalconstant and a second offset value, when the color space of the image isnot a single color space; and a pixel value replacement unit replacingthe pixel values of all the color components of the previous image, withthe correction pixel values generated in the first correction valuegeneration unit, when the color space of the image is a single colorspace, and replacing the pixel values of the first color component withthe correction pixel values generated in the first correction valuegeneration unit and replacing the pixel values of the color componentsother than the first color component with the correction pixel valuesgenerated in the second correction value generation unit, when the colorspace of the image is not a single color space.
 36. The apparatus ofclaim 35, wherein, when the color space of the image is a YCbCr or a YUVcolor space, the first color component is the Y component.
 37. Theapparatus of claim 35, wherein, when the color space of the image is anRGB color space, the first color component is the G component.
 38. Theapparatus of claim 35, wherein, when the color space of the image is anRGB color space, the color space determination unit determines that thecolor space of the image is a single color space.
 39. The apparatus ofclaim 35, wherein, when the color space of the image is a YCbCr or a YUVcolor space, the color space determination unit determines that thecolor space of the image is not a single color space.
 40. The apparatusof claim 35, wherein the entropy encoding unit performs encoding so thatinformation on whether the image is a single color space is included inthe bitstream.
 41. The apparatus of claim 35, wherein the entropyencoding unit performs encoding so that the first proportional constantand the first offset value are included in the bitstream.
 42. Theapparatus of claim 34, wherein, when the image is not a single colorspace, the entropy encoding unit performs encoding so that the secondproportional constant and the second offset value are included in thebitstream.
 43. An image decoding method of decoding an image from aninput bitstream, the method comprising: entropy decoding the bitstreamto yield entropy decoded data; inverse quantizing the entropy decodeddata to yield inverse quantized data; correcting pixel values byapplying identical correction pixel values to all color components of aprevious image, when the color space of an image is a single colorspace, and correcting pixel values by applying different correctionpixel values to the color components of the previous image, when thecolor space of the image is not a single color space; and performingtemporal prediction decoding of data corresponding to a current imageamong the inverse quantized data using the corrected pixel values of theprevious image, wherein the single color space is a color space havingcolor components including a chroma component and a luma component. 44.The method of claim 43, wherein the correcting pixel values of theprevious image comprises: correcting the pixel value of a first colorcomponent among pixel values of the previous image using a firstproportional constant and a first offset value; determining whether thecolor space of the image is a single color space; and correcting a pixelvalue corresponding to a color component other than the first colorcomponent using the first proportional constant and the first offsetvalue, when the color space of the image is a single color space, andcorrecting a pixel value corresponding to a color component other thanthe first color component using a second proportional constant and asecond offset value, when the color space of the image is not a singlecolor space.
 45. The method of claim 44, wherein, when the color spaceof the image is a YCbCr or a YUV color space, the first color componentis the Y component.
 46. The method of claim 44, wherein, when the colorspace of the image is an RGB color space, the first color component isthe G component.
 47. The method of claim 44, wherein, in the determiningwhether the color space of the image is a single color space, when thecolor space of the image is an RGB color space, it is determined thatthe color space of the image is a single color space.
 48. The method ofclaim 44, wherein, in the determining whether the color space of theimage is a single color space, when the color space of the image is anyone of YCbCr and YUV color spaces, it is determined that the color spaceof the image is not a single color space.
 49. The method of claim 44,wherein, in the determining whether the color space of the image is asingle color space, information on whether the color space of the imageis a single color space, included in the entropy decoded data, is used.50. The method of claim 44, wherein information on the firstproportional constant and the first offset value is included in theentropy decoded data.
 51. The method of claim 44, wherein information onthe second proportional constant and the second offset value is includedin the entropy decoded data.
 52. An image decoding apparatus of decodingan image from an input bitstream, the method comprising: an entropydecoding unit entropy decoding the bitstream to yield entropy decodeddata; an inverse quantization unit inverse quantizing the entropydecoded data to yield inverse quantized data; a pixel value correctionunit correcting pixel values by applying identical correction pixelvalues to all color components of a previous image, when the color spaceof an image is a single color space, and correcting pixel values byapplying different correction pixel values to the color components ofthe previous image, when the color space of the image is not a singlecolor space; and a temporal prediction decoding unit, performingtemporal prediction decoding of data corresponding to a current imageamong the inverse quantized data using the corrected pixel values of theprevious image, wherein the single color space is a color space havingcolor components including a chroma component and a luma component. 53.The apparatus of claim 52, wherein the pixel value correction unitcomprises: a first correction value generation unit generatingcorrection pixel values using a first proportional constant and a firstoffset value; a color space determination unit determining whether thecolor space of the image is a single color space; a second correctionvalue generation unit generating correction pixel values using a secondproportional constant and a second offset value, when the color space ofthe image is not a single color space; and a pixel value replacementunit replacing the pixel values of all the color components of theprevious image, with the correction pixel values generated in the firstcorrection value generation unit, when the color space of the image is asingle color space, and replacing the pixel values of the first colorcomponent with the correction pixel values generated in the firstcorrection value generation unit and replacing the pixel values of thecolor components other than the first color component with thecorrection pixel values generated in the second correction valuegeneration unit, when the color space of the image is not a single colorspace.
 54. The apparatus of claim 53, wherein, when the color space ofthe image is a YCbCr or a YUV color space, the first color component isthe Y component.
 55. The apparatus of claim 53, wherein, when the colorspace of the image is an RGB color space, the first color component isthe G component.
 56. The apparatus of claim 53, wherein, when the colorspace of the image is an RGB color space, the color space determinationunit determines that the color space of the image is a single colorspace.
 57. The apparatus of claim 53, wherein, when the color space ofthe image is a YCbCr or a YUV color space, the color space determinationunit determines that the color space of the image is not a single colorspace.
 58. The apparatus of claim 53, wherein the color spacedetermination unit determines whether the color space of the image is asingle color space using information included in the entropy decodeddata.
 59. The apparatus of claim 53, wherein information on the firstproportional constant and the first offset value is included in theentropy decoded data.
 60. The apparatus of claim 53, wherein informationon the second proportional constant and the second offset value isincluded in the entropy decoded data.
 61. A computer readable recordingmedium having embodied thereon a computer program for executing themethod of claim
 1. 62. A computer readable recording medium havingembodied thereon a computer program for executing the method of claim22.
 63. A computer readable recording medium having embodied thereon acomputer program for executing the method of claim 43.